Umstellung auf UTC Timestamp

lib/content_views/assigned_jobs_page.dart

@@ -231,7 +231,7 @@ class _AssignedJobsPageState extends State<AssignedJobsPage> with ProducerMixin,
     message.ver = job.ver.toString();
     message.item = item;
     message.track = Track();
-    message.track.time = DateTime.now().toUtc().toIso8601String();
+    message.track.time = Util.toUnixMillisUtc(DateTime.now().toUtc());
     message.track.pos = FinTaskPos();
     message.track.pos!.lat = currentPosition != null ? currentPosition.latitude : 0.0;
     message.track.pos!.long = currentPosition != null ? currentPosition.longitude : 0.0;